Hand-worn device for surface gesture input

ABSTRACT

Embodiments that relate to energy efficient gesture input on a surface are disclosed. One disclosed embodiment provides a hand-worn device that may include a microphone configured to capture an audio input and generate an audio signal, an accelerometer configured to capture a motion input and generate an accelerometer signal, and a controller comprising a processor and memory. The controller may be configured to detect a wake-up motion input based on the accelerometer signal. The controller may wake from a low-power sleep mode in which the accelerometer is turned on and the microphone is turned off and enter a user interaction interpretation mode in which the microphone is turned on. Then, the controller may contemporaneously receive the audio signal and the accelerometer signal and decode strokes. Finally, the controller may detect a period of inactivity based on the audio signal and return to the low-power sleep mode.

BACKGROUND

Gesture-based user interaction allows a user to control an electronicdevice by making gestures such as writing letters to spell words,swatting a hand to navigate a selector, or directing a remote controllerto direct a character in a video game. One way to provide for suchinteraction is to use a device such as a mobile phone or tabletcomputing device equipped with a touch screen for two-dimensional (2-D)touch input on the touch screen. But, this can have the disadvantagethat the screen is typically occluded while it is being touched, andsuch devices that include touch screens are also comparatively expensiveand somewhat large in their form factors. Another way is to use depthcameras to track a user's movements and enable three-dimensional (3-D)gesture input to a system having an associated display, and suchfunctionality has been provided in certain smart televisions and gameconsoles. One drawback with such three-dimensional gesture trackingdevices is that they have high power requirements which presentschallenges for implementation in portable computing devices, and anotherdrawback is that they typically require a fixed camera to observe thescene, also a challenge to portability. For these reasons, there arechallenges to adopting touch screens and 3-D gesture trackingtechnologies as input devices for computing devices with ultra-portableform factors, including wearable computing devices.

SUMMARY

Various embodiments are disclosed herein that relate to energy efficientgesture input on a surface. For example, one disclosed embodimentprovides a hand-worn device that may include a microphone configured tocapture an audio input and generate an audio signal, an accelerometerconfigured to capture a motion input and generate an accelerometersignal, and a controller comprising a processor and memory. Thecontroller may be configured to detect a wake-up motion input based onthe accelerometer signal. In response, the controller may wake from alow-power sleep mode in which the accelerometer is turned on and themicrophone is turned off and enter a user interaction interpretationmode in which the microphone is turned on. Then, the controller maycontemporaneously receive the audio signal and the accelerometer signaland decode strokes based on the audio signal and the accelerometersignal. Finally, the controller may detect a period of inactivity basedon the audio signal and return to the low-power sleep mode.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a hand-worn device for energy efficientgesture input on a surface, according to one embodiment.

FIG. 2 illustrates an example use of the hand-worn device of FIG. 1 toinput a gesture on the surface.

FIG. 3 is a flowchart illustrating an energy efficient method forcapturing gesture input on a surface, according to one embodiment.

FIG. 4 is a flowchart illustrating substeps of a step of the method ofFIG. 3 for decoding strokes.

FIG. 5 illustrates an example use of embodiments of the hand-worn deviceas a ring or wristband.

FIG. 6 is a simplified schematic illustration of an embodiment of acomputing system within which the hand worn device of FIG. 1 may beutilized.

FIG. 7 illustrates a hierarchical gesture classification strategy fordisambiguating different gestures.

DETAILED DESCRIPTION

FIG. 1 shows a schematic view of a hand-worn device 10 for energyefficient gesture input on a surface. The hand-worn device 10 mayinclude sensors 12 which may include a microphone 14 configured tocapture an audio input and generate an audio signal based thereon, andan accelerometer 16 configured to capture a motion input and generate anaccelerometer signal based thereon. The hand-worn device may alsoinclude a controller 18 comprising a processor 20 and memory 22, and thecontroller 18 may be configured to switch the hand-worn device 10between various operating modes to maintain energy efficiency.

When not in use, the hand-worn device 10 may operate in a low-powersleep mode in which the accelerometer 16 is turned on and the microphone14 is turned off. The accelerometer 16 may itself operate in a low-powermotion-detection mode, which may include only detecting motion inputabove a predetermined threshold. The controller 18 may then detect awake-up motion input of a user based on the accelerometer signal fromthe accelerometer 16. The wake-up motion input may be from a wake-upgesture of the user such as a tap that exceeds a predetermined thresholdin the accelerometer signal. Multiple taps or other suitable gesturesmay be used to prevent accidental waking by incidental user motions.Upon detecting the wake-up motion input, the controller 18 may wake fromthe low-power sleep mode and enter a user interaction interpretationmode in which the microphone 14 is turned on and the accelerometer 16 isfully active.

During the user interaction interpretation mode, the controller 18 maycontemporaneously receive the audio signal from the microphone 14 andthe accelerometer signal from the accelerometer 16. The controller 18may then execute a stroke decoder 24 to decode strokes based on theaudio signal and the accelerometer signal. Once the user has finishedgesturing, the controller 18 may detect a period of inactivity based onthe audio signal from the microphone 14 and return to the low-powersleep mode. The period of inactivity may be preset, such as 30 seconds,1 minute, or 5 minutes, may be a user input period of time, or may be aperiod set through machine learning techniques that analyze patterns ofaccelerometer and audio signals and the periods of inactivity that arelikely to follow.

Decoding strokes on the hand-worn device 10 may involve breakinggestures down into simple geometric patterns such as orthogonal ordiagonal line segments and half circles. The strokes may make up lettersor context-dependent symbols, etc. The stroke decoder 24 may comprise astroke classifier which may be, for example, a support vector machine(SVM) classifier, and the SVM classifier may save energy by only lookingfor a predetermined set of strokes. Additionally, the stroke decoder 24may be programmed to recognize taps and swipes based on a threshold ofthe accelerometer signal and a length of the audio signal. Further,orthogonal and diagonal scrolls are detectable, depending on the contextof the gesture input, as explained below. Device 10 may be configured torecognize more complicated gestures as well, although recognition ofmore complicated gestures may require a concomitant increase in powerconsumed during disambiguation and/or degrade performance.

The hand-worn device 10 may include an audio processing subsystem 26with a band-pass filter 28 configured to filter the audio signal, anamplifier 30 configured to amplify the audio signal, and an envelopedetector 32 such as, for example, a threshold based envelope detector,configured to generate an audio envelope from the audio signal. Usingthese components, the audio processing subsystem 26 may transform theaudio signal into an audio envelope by filtering the audio signal,amplifying the audio signal, and generating an audio envelope from theaudio signal. The controller 18 may then decode strokes with the strokedecoder 24 based on the audio envelope of the audio signal, rather thanthe audio signal itself, and the accelerometer signal. The audioprocessing subsystem 26 may be formed separately from the microphone 14,or one or more parts within the audio processing subsystem 26 may beincorporated into the microphone 14, for example. Additionally, morethan one band-pass filter 28 and more than one amplifier 30 may beincluded.

Gesture input may take place in many different situations with differentsurroundings, as well as on a variety of different types of surfaces.The audio input detected by the microphone 14 may be the sound of skindragging across a surface, as one example. Sound may be produced in thesame frequency band regardless of the composition of the surface, thusthe surface may be composed of wood, plastic, paper, glass, cloth, skin,etc. As long as the surface generates enough friction when rubbed withskin to produce an audio input detectable by the microphone 14,virtually any sturdy surface material may be used. Additionally, anysuitable surface that is close at hand may be used, such that it may notbe necessary to gesture on only one specific surface, increasing theutility of the hand worn device 10 in a variety of environments.

The audio input, being thus produced by skin dragging across thesurface, may be used to determine when the user is gesturing. However,the audio input may not always be easily distinguished from ambientnoise. The audio processing subsystem 26 may filter the audio signalwith at least one band-pass filter 28 to remove ambient noise and leaveonly the audio signal due to skin dragging across the surface.Generating an audio envelope of the audio signal may keep the length andamplitude of the audio signal for decoding strokes while discarding datathat may not be used, both simplifying computation and saving thehand-worn device 10 energy.

The hand-worn device 10 may further comprise a battery 34 configured tostore energy and energy harvesting circuitry 36 including an energyharvesting coil 38. The energy harvesting circuitry 36 may include acapacitor. The energy harvesting circuitry 36 may be configured tosiphon energy from a device other than the hand-worn device via awireless energy transfer technique such as near-field communication(NFC) or an inductive charging standard, and charge the battery with thesiphoned energy. The energy may be siphoned from a mobile phone with NFCcapabilities, for example. Simply holding the mobile phone may put thehand-worn device 10 in close proximity to an NFC chip in the mobilephone, allowing the hand-worn device 10 to charge the battery 34throughout the day through natural actions of the user and withoutrequiring removal of the hand-worn device 10.

In another example, the hand-worn device 10 may utilize a charging pador other such charging device to charge the battery 34. If the user doesnot wish to wear the hand-worn device 10 at night, such a charging padmay be used by placing the hand-worn device 10 on it while the usersleeps, for example. However, removal may not be necessary. Forinstance, the charging pad may be placed under a mouse or other suchinput device while the user operates a personal computer, allowing thehand-worn device 10 to be charged while the user works.

The hand-worn device 10 may further comprise a radio 40 and thecontroller 18 may be configured to send a gesture packet 42 to acomputing device 44 via the radio 40. Typically the radio includes awireless transceiver configured for two way communication, which enablesacknowledgments of transmissions to be sent from the computing deviceback to the hand worn device. In other embodiments, a radio 40 includinga one way transmitter may be used. The computing device may be thedevice from which the hand-worn device siphons energy, but energy mayalso be siphoned from a separate device. The gesture packet 42 maycomprise the decoded strokes and inter-stroke information. Theinter-stroke information may comprise inter-stroke duration, which isthe time between decoded strokes, and data indicating whether a userremains in contact with the surface or does not remain in contact withthe surface between decoded strokes. These two factors may be taken intoaccount when assembling the decoded strokes into different letters, forexample. One letter may be gestured with two consecutive strokes withoutlifting, and one may be gestured with the same two stokes, but the usermay lift off the surface and reposition for the second stroke.

The computing device may comprise an application programming interface(API) 46 configured to receive the gesture packet 42 and decode anapplication input corresponding to the gesture packet 42. Sending agesture packet 42 rather than raw signals may greatly reduce the amountof energy the hand-worn device 10 may spend, since the gesture packet 42may be much smaller than the corresponding audio signal andaccelerometer signal.

The application input may be letters, symbols, or commands, for example.Commands may include scrolling, changing pages, zooming in or out,cycling through displayed media, selecting, changing channels, andadjusting volume, among others. The API 46 may provide context to thestroke decoder 24 such that the stroke decoder 24 may only recognize,for example, strokes of letters for text entry or scrolls for scrollingthrough displayed pages. Such gestures may be difficult to disambiguatewithout context from the API 46.

The computing device 44 may be any of a wide variety of devices fordifferent uses. For example, the computing device 44 may be a devicethat controls a television. The hand-worn device 10 may receive gestureinput that corresponds to application input to change the channel on thetelevision or adjust the volume. In this case, the surface may be acouch arm or the user's own leg. In another example, the computingdevice 44 may control a television and allow a user to stream movies. Inthis case, the hand-worn device 10 may receive a swipe or scrollapplication input to browse through movies, or it may allow the user toinput letters to search by title, etc. In another example, the computingdevice 44 may control display of a presentation. The user may controlslides without holding onto a remote which is easily dropped.

In another example, the computing device 44 may allow a user to access aplurality of devices. In such a situation, the user may be able to, forexample, turn on various appliances in a home, by using one hand-worndevice 10. Alternatively, the user may be able to switch between devicesthat share a common display, for example. In yet another example, thecomputing device 44 may control a head-mounted display (HMD) or be awatch or mobile phone, where space for input on a built-in surface islimited. For instance, if the computing device 44 is a mobile phone, itmay ring at an inopportune time for the user. The user may franticallysearch through pockets and bags to find the mobile phone and silence theringer. However, by using the hand-worn device 10, the user may easilyinteract with the mobile phone from a distance. In such instances, thehand-worn device 10 may be constantly available due to being worn by theuser.

FIG. 2 illustrates an example use of the hand-worn device 10 to input agesture on the surface, utilizing the hardware and software componentsof FIG. 1. In this example, the hand-worn device 10 is a ring, which maybe the size and shape of a typical ring worn as jewelry. However, othermanifestations may be possible, such as a watch, wristband, fingerlessglove, or other hand-worn device. In this instance, the user isgesturing the letter “A” with his finger on a table, providing a gestureinput 48. However, in an instance where the user does not have a fingeror otherwise cannot gesture with a finger, another digit or anappendage, for example, may serve to enact the gesture. In order for themicrophone 14 to capture an audio input 50, skin is typically draggedacross a surface, and in order for the accelerometer 16 to capture amotion input 52, the accelerometer 16 is typically placed near enough towhere the user touches the surface to provide a useable accelerometersignal 54.

To account for different users, surfaces, and situations, theaccelerometer 16 may be further configured to determine a tilt of thehand-worn device 10 after detecting the wake-up motion input. A givensurface may not be perfectly horizontal, or the user may slightly tilther finger, for example. Tilt determination may be used to convert X-,Y-, and Z-components of the accelerometer signal 54 to X-, Y-, andZ-components with respect to an interacting plane of the surface.

As mentioned above, the microphone 14 may generate the audio signal 56,which may then be received by the audio processing subsystem 26 togenerate the audio envelope 58. The audio envelope 58 may be received bythe stroke decoder 24 of the controller 18, along with the accelerometersignal 54. The stroke decoder 24 may decode strokes based on the audioenvelope 58 and the accelerometer signal 54 and generate a gesturepacket 42. The gesture packet 42 may be sent to the computing device 44,in this case a personal computer, where the API 46 may decode anapplication input 60 corresponding to the gesture packet 42. In thisexample, the application input 60 includes displaying the letter “A”.

The controller 18 may be further configured to receive feedback 62 fromthe user indicating that the application input 60 is correct orincorrect. In this example, the feedback 62 is received by selecting ornot selecting the cancel option X displayed by the computing device 44.In other examples, the feedback 62 may be received by the hand-worndevice 10 by shaking the hand-worn device 10, etc., to cancel therecognition phase and start gesture input again or to select a differentrecognition candidate. Based on this feedback 62, the controller 18 mayapply a machine learning algorithm to accelerometer samples of theaccelerometer signal 54 to statistically identify accelerometer samples54A that are likely to be included in the decoded strokes, and eliminateother accelerometer samples that are unlikely to be included. Moregenerally, based on the feedback 62, the controller 18 may adjustparameters 64 of the stroke decoder 24.

In this way, the stroke decoder 24 may use only the most relevantaccelerometer samples 54A along with the audio envelope 58 when decodingstrokes. This may allow the stroke decoder 24 to use simple arithmeticoperations for low-power stroke classification and avoid usingtechniques such as dynamic time warping and cross correlations that mayuse complex mathematical operations and/or a greater number ofaccelerometer samples, which may lead to a higher energy consumption.Instead, the hand-worn device 10 may be further configured to consume nomore than 1.5 mA and preferably no more than 1.2 mA in the userinteraction interpretation mode and no more than 1.0 μA and preferablyno more than 0.8 μA in the low-power sleep mode.

FIG. 3 illustrates a flowchart of an energy efficient method, method300, for capturing gesture input on a surface with a hand-worn device.The hand-worn device may be a ring, watch, wristband, glove, or otherhand-worn device, for example. The following description of method 300is provided with reference to the software and hardware components ofthe hand-worn device 10 and computing device 44 described above andshown in FIGS. 1 and 2. It will be appreciated that method 300 may alsobe performed in other contexts using other suitable hardware andsoftware components.

With reference to FIG. 3, at 302 the method 300 may include detecting awake-up motion input based on an accelerometer signal from anaccelerometer. At 304 the method 300 may include waking from a low-powersleep mode in which the accelerometer is turned on and a microphone isturned off and entering a user interaction interpretation mode in whichthe microphone is turned on. In addition, after detecting the wake upmotion input, the hand worn device may be configured to begin detectinga tilt of the hand worn device at the accelerometer.

At 306 the method 300 may include contemporaneously receiving an audiosignal from the microphone and the accelerometer signal. At 308 themethod 300 may include decoding strokes based on the audio signal andthe accelerometer signal. At 310 the method 300 may include detecting aperiod of inactivity based on the audio signal, which may be of thelength described above, input by a user, or learned over time by thehand worn device. At 312 the method 300 may include returning to thelow-power sleep mode. After 312 the method 300 may include ending orcontinuing to operate in a sleep-wake cycle by returning to 302.

It will be appreciated as described above that the hand-worn device mayfurther comprise a battery and energy harvesting circuitry including anenergy harvesting coil, and thus at any point throughout method 300, themethod may include siphoning energy from a device other than thehand-worn device via a wireless energy transfer technique such asnear-field communication (NFC) at the energy harvesting circuitry andcharging the battery with the siphoned energy. The energy may besiphoned from a device such as an NFC capable smartphone or chargingpad, for example. Combining the low power consumption of the device withenergy siphoning abilities may allow the user to wear the hand-worndevice at all times without removing it for charging. This may reducethe likelihood of dropping, losing, or forgetting the hand-worn device,incorporating the use and presence of the hand-worn device into dailylife.

FIG. 4 is a flowchart illustrating detailed substeps of step 308,decoding strokes, of method 300 of FIG. 3. At 320 the method 300 mayinclude filtering the audio signal with a band-pass filter of an audioprocessing subsystem of the hand-worn device. The audio processingsubsystem may further comprise at least one amplifier and an envelopedetector. At 322 the method 300 may include amplifying the audio signalwith the amplifier. At 324 the method 300 may include generating anaudio envelope from the audio signal with an envelope detector. At 326the method 300 may include decoding strokes based on the audio envelopeof the audio signal and the accelerometer signal.

At 328 the method 300 may include sending a gesture packet to acomputing device via a radio, the gesture packet comprising the decodedstrokes and inter-stroke information. The inter-stroke information maycomprise inter-stroke duration and data indicating whether a userremains in contact with the surface or does not remain in contact withthe surface between decoded strokes. At 330 the method 300 may includereceiving the gesture packet at an application programming interface(API) of the computing device and decoding an application inputcorresponding to the gesture packet at the API. After 330, the step 308of method 300 may end. However, it may also proceed to 332 to begin afeedback process.

At 332 the method 300 may include receiving feedback from the userindicating that the application input is correct or incorrect. At 334the method 300 may include, based on the feedback, adjusting parametersof a stroke decoder. After 336, the method 300 may include returning to326 decode strokes more efficiently than before receiving feedback.

It will be appreciated that method 300 is provided by way of example andis not meant to be limiting. Therefore, it is to be understood thatmethod 300 may include additional and/or alternative steps than thoseillustrated in FIGS. 3 and 4. Further, it is to be understood thatmethod 300 may be performed in any suitable order. Further still, it isto be understood that one or more steps may be omitted from method 300without departing from the scope of this disclosure.

FIG. 5 illustrates example embodiments of the hand-worn device as a ringor wristband, though it may also be another hand-worn device such as afingerless glove, for example. The user may wear the ring on a finger orthe wristband on a wrist. The surface upon which the user is gesturingis a countertop in this example. The wide arrow indicates the movementof the user dragging her finger along the countertop to provide agesture input, and her entire hand, including the hand-worn device, maymove in nearly or exactly the same manner as her finger, such that theaccelerometer in the hand-worn device may generate an accelerometersignal with accuracy. The friction generated between the countertop andthe user's finger may produce sound waves as visually represented inFIG. 5. The sound waves may serve as an audio input and the thin arrowsmay demonstrate the microphone in the hand-worn device capturing theaudio input.

FIG. 7 illustrates a hierarchical gesture classification strategy fordisambiguating different gestures. Disambiguating gestures in tiers inthis manner may allow for higher accuracy in detecting and interpretinggestures as well as reduced energy consumption. At each tier,disambiguation is performed to eliminate gesture candidates, and narrowthe field of possible matching gestures. By utilizing a gesturerecognition algorithm that traverses a disambiguation tree in thismanner, the total processing power consumed for matching a gesture maybe reduced, since possible candidates are eliminated at each fork in thehierarchy. As described above, not only may gestures be broken down intostrokes and reassembled as letters, characters, shapes, symbols, etc.,but gestures such as scrolls, swipes, and taps may also be decoded withdifferent classifiers.

With reference to FIG. 7, at 702 the start of a gesture may be detectedby the audio envelope indicating that skin is moving across a surface.From here, the magnitude of the Z-component of the accelerometer signalmay be compared to a threshold value to classify the gesture as either ahard landing or a soft landing. At 704 a soft landing may be determinedif the Z-component is under the threshold. Alternatively, at 706 a hardlanding may be determined if the Z-component is equal to or over thethreshold. The types of landing may be classified by a landingclassifier of the stroke decoder.

Context from the API may be used to further classify the gesture with asoft landing into either a stroke or series of strokes at X08 or ascroll at X10. The context may be, for example, that the API will accepttext input (stroke), invoking the stroke classifier of the strokedecoder, or page navigation (scroll), invoking a scroll classifier ofthe stroke decoder. Any or all of the landing classifier, the strokeclassifier, and the scroll classifier may be an SVM classifier, forexample. If the gesture is determined to be a scroll, the beginning ofthe gesture may be a short nudge. After the nudge is detected, theremainder of the gesture may be interpreted in real-time such thatdifferent directions of scrolling are determined based upon theaccelerometer signal.

A gesture with a hard landing may be further disambiguated by aswipe-tap classifier using the length of the audio envelope. At 712 atap may be determined by a very short audio envelope, i.e. it is under athreshold. At 714 a swipe may be determined by a longer audio envelope,i.e. it is greater than or equal to the threshold. A swipe may befurther disambiguated by direction according to the accelerometersignal. In this manner, a variety of gesture inputs may be disambiguatedby traversing a tiered classifier as shown in FIG. 7, thus conservingprocessor time and power consumption as compared to attempting todisambiguate a wide class of gestures in a single step.

The above described systems and methods may be used to provide energyefficient gesture input on a surface using a hand-worn device. Thehand-worn device may be adapted in different embodiments to serve avariety of purposes. This approach has the potential advantages ofconstant availability, low power consumption, battery charging with orwithout removing the hand-worn device, accurate capture of user intent,and versatility.

In some embodiments, the methods and processes described herein may betied to a computing system of one or more computing devices or hand-worndevices. In particular, such methods and processes may be implemented asa computer-application program or service, an application-programminginterface (API), a library, and/or other computer-program product.

FIG. 6 schematically shows a non-limiting embodiment of a computingsystem 600 that can enact one or more of the methods and processesdescribed above. Hand-worn device 10 and computing device 44 may takethe form of computing system 600. Computing system 600 is shown insimplified form. Computing system 600 may take the form of one or morepersonal computers, server computers, tablet computers,home-entertainment computers, network computing devices, gaming devices,mobile computing devices, mobile communication devices (e.g.,smartphone), hand-worn devices, and/or other computing devices.

Computing system 600 includes a logic subsystem 604 and a storagesubsystem 608. Computing system 600 may optionally include a displaysubsystem 612, sensor subsystem 620, input subsystem 622, communicationsubsystem 616, and/or other components not shown in FIG. 6.

Logic subsystem 604 includes one or more physical devices configured toexecute instructions. For example, the logic subsystem may be configuredto execute instructions that are part of one or more applications,services, programs, routines, libraries, objects, components, datastructures, or other logical constructs. Such instructions may beimplemented to perform a task, implement a data type, transform thestate of one or more components, achieve a technical effect, orotherwise arrive at a desired result.

The logic subsystem may include one or more processors configured toexecute software instructions. Additionally or alternatively, the logicsubsystem may include one or more hardware or firmware logic subsystemsconfigured to execute hardware or firmware instructions. Processors ofthe logic subsystem may be single-core or multi-core, and theinstructions executed thereon may be configured for sequential,parallel, and/or distributed processing. Individual components of thelogic subsystem optionally may be distributed among two or more separatedevices, which may be remotely located and/or configured for coordinatedprocessing. Aspects of the logic subsystem may be virtualized andexecuted by remotely accessible, networked computing devices configuredin a cloud-computing configuration.

Storage subsystem 608 includes one or more physical devices configuredto hold instructions executable by the logic subsystem to implement themethods and processes described herein. When such methods and processesare implemented, the state of storage subsystem 608 may betransformed—e.g., to hold different data.

Storage subsystem 608 may include removable devices 624 and/or built-indevices. Storage subsystem 608 may include optical memory (e.g., CD,DVD, HD-DVD, Blu-Ray Disc, etc.), semiconductor memory (e.g., RAM,EPROM, EEPROM, etc.), and/or magnetic memory (e.g., hard-disk drive,floppy-disk drive, tape drive, MRAM, etc.), among others. Storagesubsystem 608 may include volatile, nonvolatile, dynamic, static,read/write, read-only, random-access, sequential-access,location-addressable, file-addressable, and/or content-addressabledevices.

It will be appreciated that storage subsystem 608 includes one or morephysical devices. However, aspects of the instructions described hereinalternatively may be propagated by a communication medium (e.g., anelectromagnetic signal, an optical signal, etc.) that is not held by aphysical device for a finite duration.

Aspects of logic subsystem 604 and storage subsystem 608 may beintegrated together into one or more hardware-logic components. Suchhardware-logic components may include field-programmable gate arrays(FPGAs), program and application-specific integrated circuits(PASIC/ASICs), program- and application-specific standard products(PSSP/ASSPs), system-on-a-chip (SOC), and complex programmable logicdevices (CPLDs), for example.

The terms “module” and “program” may be used to describe an aspect ofcomputing system 600 implemented to perform a particular function. Insome cases, a module or program may be instantiated via logic subsystem604 executing instructions held by storage subsystem 608. It will beunderstood that different modules, programs, and/or subsystems may beinstantiated from the same application, service, code block, object,library, routine, API, function, etc. Likewise, the same module,program, and/or subsystem may be instantiated by different applications,services, code blocks, objects, routines, APIs, functions, etc. Theterms “module” and “program” may encompass individual or groups ofexecutable files, data files, libraries, drivers, scripts, databaserecords, etc.

When included, display subsystem 612 may be used to present a visualrepresentation of data held by storage subsystem 608. This visualrepresentation may take the form of a graphical user interface (GUI). Asthe herein described methods and processes change the data held by thestorage subsystem, and thus transform the state of the storagesubsystem, the state of display subsystem 612 may likewise betransformed to visually represent changes in the underlying data.Display subsystem 612 may include one or more display devices utilizingvirtually any type of technology. Such display devices may be combinedwith logic subsystem 604 and/or storage subsystem 608 in a sharedenclosure, or such display devices may be peripheral display devices.

When included, communication subsystem 616 may be configured tocommunicatively couple computing system 600 with one or more othercomputing devices. Communication subsystem 616 may include wired and/orwireless communication devices compatible with one or more differentcommunication protocols. As non-limiting examples, the communicationsubsystem may be configured for communication via a radio, a wirelesstelephone network, or a wired or wireless local- or wide-area network.In some embodiments, the communication subsystem may allow computingsystem 600 to send and/or receive messages to and/or from other devicesvia a network such as the Internet.

When included, sensor subsystem 620 may include one or more sensorsconfigured to sense different physical phenomena (e.g., visible light,infrared light, sound, acceleration, orientation, position, etc.).Sensor subsystem 620 may be configured to provide sensor data to logicsubsystem 604, for example.

When included, input subsystem 622 may comprise or interface with one ormore user-input devices such as a keyboard, mouse, touch screen, or gamecontroller. In some embodiments, the input subsystem may comprise orinterface with selected natural user input (NUI) componentry. Suchcomponentry may be integrated or peripheral, and the transduction and/orprocessing of input actions may be handled on- or off-board. Example NUIcomponentry may include a microphone for speech and/or voicerecognition; an infrared, color, stereoscopic, and/or depth camera formachine vision and/or gesture recognition; a head tracker, eye tracker,accelerometer, and/or gyroscope for motion detection and/or intentrecognition; as well as electric-field sensing componentry for assessingbrain activity. It will be appreciated that computing system 600 mayfunction as computing device 44 describe above and shown in FIGS. 1 and2, and the hand-worn device 10 may be an input device of input subsystem622.

It will be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated and/ordescribed may be performed in the sequence illustrated and/or described,in other sequences, in parallel, or omitted. Likewise, the order of theabove-described processes may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

The invention claimed is:
 1. A hand-worn device for energy efficientgesture input on a surface, comprising: a microphone configured tocapture an audio input and generate an audio signal; an accelerometerconfigured to capture a motion input and generate an accelerometersignal; and a controller comprising a processor and memory; wherein thecontroller is configured to: detect a wake-up motion input based on theaccelerometer signal; wake from a low-power sleep mode in which theaccelerometer is turned on and the microphone is turned off and enter auser interaction interpretation mode in which the microphone is turnedon; contemporaneously receive the audio signal and the accelerometersignal; decode strokes based on the audio signal and the accelerometersignal; detect a period of inactivity based on the audio signal; andreturn to the low-power sleep mode.
 2. The hand-worn device of claim 1,further comprising an audio processing subsystem, comprising: aband-pass filter configured to filter the audio signal; an amplifierconfigured to amplify the audio signal; and an envelope detectorconfigured to generate an audio envelope from the audio signal; whereinthe audio processing subsystem is configured to transform the audiosignal into an audio envelope by filtering the audio signal, amplifyingthe audio signal, and generating an audio envelope from the audiosignal; and wherein the controller is configured to decode strokes basedon the audio envelope of the audio signal and the accelerometer signal.3. The hand-worn device of claim 1, further comprising a radio, whereinthe controller is configured to send a gesture packet to a computingdevice via the radio, the gesture packet comprising the decoded strokesand inter-stroke information.
 4. The hand-worn device of claim 3,wherein the inter-stroke information comprises inter-stroke duration anddata indicating whether a user remains in contact with the surface ordoes not remain in contact with the surface between decoded strokes. 5.The hand-worn device of claim 3, wherein the computing device comprisesan application programming interface (API) configured to receive thegesture packet and decode an application input corresponding to thegesture packet.
 6. The hand-worn device of claim 5, wherein thecontroller is further configured to receive feedback from the userindicating that the application input is correct or incorrect, and basedthereon, adjust parameters of a stroke decoder.
 7. The hand-worn deviceof claim 1, further comprising: a battery configured to store energy;and energy harvesting circuitry including an energy harvesting coil,configured to siphon energy from a device other than the hand-worndevice via a wireless energy transfer technique; wherein the energyharvesting circuitry is configured to charge the battery with thesiphoned energy.
 8. The hand-worn device of claim 1, wherein thehand-worn device is a ring.
 9. The hand-worn device of claim 1, whereinthe accelerometer is further configured to determine a tilt of thehand-worn device after detecting the wake-up motion input.
 10. Thehand-worn device of claim 1, further configured to consume no more than1.5 mA in the user interaction interpretation mode and no more than 1.0μA in the low-power sleep mode.
 11. In a hand-worn device, an energyefficient method for capturing gesture input on a surface, comprising:detecting a wake-up motion input based on an accelerometer signal froman accelerometer; waking from a low-power sleep mode in which theaccelerometer is turned on and a microphone is turned off and entering auser interaction interpretation mode in which the microphone is turnedon; contemporaneously receiving an audio signal from the microphone andthe accelerometer signal; decoding strokes based on the audio signal andthe accelerometer signal; detecting a period of inactivity based on theaudio signal; and returning to the low-power sleep mode.
 12. The methodof claim 11, further comprising: filtering the audio signal with aband-pass filter of an audio processing subsystem; amplifying the audiosignal with an amplifier of the audio processing subsystem; generatingan audio envelope from the audio signal with an envelope detector of theaudio processing subsystem; and decoding strokes based on the audioenvelope of the audio signal and the accelerometer signal.
 13. Themethod of claim 11, further comprising sending a gesture packet to acomputing device via a radio, the gesture packet comprising the decodedstrokes and inter-stroke information.
 14. The method of claim 13,wherein the inter-stroke information comprises inter-stroke duration anddata indicating whether a user remains in contact with the surface ordoes not remain in contact with the surface between decoded strokes. 15.The method of claim 13, further comprising receiving the gesture packetat an application programming interface (API) of the computing deviceand decoding an application input corresponding to the gesture packet atthe API.
 16. The method of claim 15, further comprising: receivingfeedback from the user indicating that the application input is corrector incorrect; based thereon, adjusting parameters of a stroke decoder.17. The method device of claim 11, wherein the hand-worn device furthercomprises a battery and energy harvesting circuitry including an energyharvesting coil, the method further comprising: siphoning energy from adevice other than the hand-worn device via a wireless energy transfertechnique at the energy harvesting circuitry; and charging the batterywith the siphoned.
 18. The method of claim 11, wherein the hand-worndevice is a ring.
 19. The method of claim 11, further comprisingdecoding scrolls, swipes, or taps based on the audio signal and theaccelerometer signal.
 20. A hand-worn device for energy efficientgesture input on a surface, wherein the hand-worn device is a ring,comprising: a microphone configured to capture an audio input andgenerate an audio signal; an accelerometer configured to capture amotion input and generate an accelerometer signal; a controllercomprising a processor and memory; an audio processing subsystem,comprising: a band-pass filter configured to filter the audio signal; anamplifier configured to amplify the audio signal; and an envelopedetector configured to generate an audio envelope from the audio signal;and a radio; wherein the controller is configured to: detect a wake-upmotion input via based on the accelerometer signal from theaccelerometer; wake from a low-power sleep mode in which theaccelerometer is turned on and the microphone is turned off and enter auser interaction interpretation mode in which the microphone is turnedon; contemporaneously receive the audio signal and the accelerometersignal; receive the audio envelope from the audio processing subsystem;decode strokes based on the audio envelope of the audio signal and theaccelerometer signal; send a gesture packet to a computing device viathe radio, the gesture packet comprising the decoded strokes andinter-stroke information; detect a period of inactivity based on theaudio signal from the microphone; and return to the low-power sleepmode.